Best you can expect out of the 3820 folding wise is about 45-47K ppd @ 4.6GHz, 3770K can hit over 50-54K ppd on the same WU's at the same 4.6GHz & lower power consumption... Like I mentioned in your build thread, the 3770K is a better CPU in every possible way... But at least you have the option to upgrade to Ivy Bridge E in 9.5 months!!!
Of course those numbers are only from a few select WU's worth 600 points before bonuses, and a fairly high overclock.
More realistically, you should see 22k - 34k ppd (depending on WU's folded) from the 3820 if you manage to reach 4.6GHz - that's running the Windows Client version 7.2.9. Hell, even my 3930K only averaged about 35-45K ppd with a modest overclock to 4.4GHz & that's with 50% more threads running (12 Vs
than the 3820, though on those aforementioned 600 pointers @ 4.6GHz I was hitting right at 87K ppd!
Good news on the 670, Gero is a bit low on his estimate, your ppd on the low side should be around 28-30K ppd on the current 3,874 point Work Units (I'm hitting 26,800 on an overclocked 660Ti), & on the high side ~45-47K ppd on the 14,093 point Work Units.
All-in all, there's a lot of folks gonna be wishing they had that kind of folding muscle under their belts !!! Congrats on the build & welcome back into the "Fold"... pun intended